Altered renal kallikrein and renin gene expression in nephrotic rats and modulation by converting enzyme inhibition.

Urinary kallikrein excretion (UKE) is decreased in rats with passive Heymann nephritis (PHN), but increases after converting enzyme inhibition (CEI). Although CEI potentiates bradykinin activity, neither the effect of CEI on kallikrein secretion nor the abnormal renal kallikrein metabolism in PHN has been examined previously. To determine the mechanism by which CEI increases UKE, normal rats and PHN received enalapril, 40 mg/kg per d orally for 4 d. UKE was 85% lower in PHN than in normals and increased in both groups after CEI, although UKE in PHN remained significantly less than in normals. Kallikrein mRNA was significantly lower in PHN compared to normals but not in PHN treated with CEI and did not change in normal rats. Renin mRNA was significantly lower in PHN, and was stimulated by CEI only in normals. Renal kallikrein and renin content were not different and were not altered by CEI. Both kallikrein and renin genes appear to be transcriptionally suppressed in rats with PHN and the depressed kallikrein mRNA levels can be reversed by CEI. The modest increase in UKE despite normalization of kallikrein mRNA after CEI suggests that there is also a posttranscriptional defect in synthesis and/or secretion of kallikrein.

Proteinuria, not altered albumin metabolism, affects hyperlipidemia in the nephrotic rat.

It has been established previously that nephrotic hyperlipidemia is characterized by both an increase in lipid synthesis and a defect in removal of lipoproteins. The relationship between these defects and altered albumin metabolism is uncertain. One hypothesis is that hepatic lipogenesis increases in parallel with albumin synthesis. To test this hypothesis, albumin synthesis was increased in nephrotic rats fed an 8.5% protein diet (LPN) by increasing dietary protein to 40% (HPN). Proteinuria was modulated in half of the rats fed 40% protein by enalapril (HPE). Albumin synthesis was the same in both HPN and HPE, but proteinuria was reduced in HPE compared to HPN, and so were serum cholesterol and triglycerides (TG). To examine the effect of serum albumin on lipid clearance in the absence of proteinuria, plasma clearance of chylomicrons (CM) and VLDL was measured in Nagase analbuminemic rats (NAR) and found to be no different than in normal SD rats. When proteinuria was induced in NAR and in SD rats, a severe and identical defect in both CM and VLDL clearance was acquired in both groups and blood lipid levels were increased to a similar degree in both groups. Neither hyperlipidemia nor defective removal of lipoproteins from the circulation are linked to albumin synthesis or serum albumin concentration but result, at least in part, from proteinuria. Postheparin lipoprotein lipase (LPL) activity was reduced slightly in nephrotic animals compared to nonnephrotic controls, but the most striking finding was a highly significant decrease in postheraprin LPL activity in normal NAR compared to SD rats (P less than 0.001), suggesting that reduced LPL activity is not responsible for reduced clearance of CM and VLDL in nephrotic rats.

A low-protein diet restricts albumin synthesis in nephrotic rats.

High-protein diets increase albumin synthesis in rats with Heymann nephritis but albuminuria increases also, causing serum albumin concentration to be suppressed further than in nephrotic animals eating a low-protein diet. Experiments were designed to determine whether dietary protein augmentation directly stimulates albumin synthesis, or whether instead increased albumin synthesis is triggered by the decrease in serum albumin concentration. Evidence is presented that dietary protein augmentation directly stimulates albumin synthesis, accompanied by a proportional increase in steady-state hepatic albumin mRNA concentration (AlbmRNA) and by an increase in AlbmRNA transcription. When the increased albuminuria resulting from dietary protein augmentation is blunted with enalapril, serum albumin concentration is shown to increase in nephrotic rats. Both albumin synthesis and AlbmRNA increase in these animals despite the greater serum albumin concentration. Albumin synthesis correlates inversely with both serum albumin and serum oncotic pressure in nephrotic rats fed 40% protein, but does not correlate with serum albumin concentration in nephrotic rats fed 8.5% protein (LP), even when serum albumin concentration is reduced. Albumin masses are preserved in LP primarily because of reduced albuminuria. Reduced serum oncotic pressure and dietary protein augmentation combine to stimulate albumin synthesis in nephrotic rats at the level of gene transcription.

High protein diets stimulate albumin synthesis at the site of albumin mRNA transcription.

High dietary protein intake directly stimulates albumin synthesis ald albuminuria in rats with Heymann nephritis. Increased albumin synthetic rate might be due to the presence of increased amino acids available for protein synthesis causing more efficient translation of preformed albumin mRNA, or instead might be linked to increased steady state albumin mRNA levels in the liver. Albumin synthesis, hepatic albumin mRNA content, and albumin mRNA relative to beta actin mRNA (as an internal control) (Alb/beta Act), were measured in rats with Heymann nephritis fed either 8.5% protein (LP), or after protein intake was increased to 40% for 4 days (HP). enalapril (E) was used to modulate the proteinuric effect of HP, yielding four experimental groups, LPN (8.5% protein nephrotic, no enalapril), LPE (8.5% protein, enalapril treated), HPN (40% protein nephrotic, no enalapril), and HPE (40% protein, enalapril treated). Dietary protein augmentation increased the rate of albumin synthesis, steady-state albumin mRNA levels, and Alb/beta Act in both HPN and HPE, compared to either LPH or LPE, even though serum albumin concentration was greater in HPE than in either of the groups fed LP. Both albumin mRNA and Alb/beta Act correlated with the rate of albumin synthesis (r = 0.531, P less than 0.05; and 0.553, P less than 0.01 respectively). Nuclear run-on assays were performed using nuclei isolated from the livers of LPN or HPN to determine whether increased albumin mRNA resulted from an increase in the rate of albumin mRNA transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary protein intake and angiotensin converting enzyme inhibition in Heymann nephritis.

The effect of diets containing 8.5%, 21% or 40% protein on growth, urinary albumin excretion and serum albumin concentration was determined in rats with Heymann nephritis and in non-nephrotic control animals. Urinary albumin excretion was greater in nephrotic rats with each increment in dietary protein intake, and serum albumin concentration tended to be least in nephrotic rats fed 40% protein. Albuminuria decreased spontaneously and serum albumin concentration increased in nephrotic rats fed 8.5% protein for 25 days. Enalapril treatment caused a further reduction in urinary albumin excretion and an increase in serum albumin concentration in nephrotic rats fed 8.5% protein. Albuminuria did not decrease nor did serum albumin concentration increase in nephrotic rats fed 40% protein without enalapril treatment, but enalapril caused a significant reduction in urinary albumin excretion and an increase in serum albumin concentration in nephrotic rats fed either 8.5% or 40% protein. The rate of growth in normal rats was greatest when they were fed 21% protein, compared to either 8.5% or 40% protein. Growth rate was significantly reduced in nephrotic rats, regardless of dietary protein intake and regardless of treatment with enalapril, but the 21% protein diet still induced the most rapid rate of growth. Growth rate was not significantly different in nephrotic rats fed either 40% or 8.5% protein. The difference in weight between pair fed nephrotic and control animals fed 21% protein was due to a decrease in carcass and skin weight in nephrotic animals. Carcass protein was significantly reduced in the nephrotic animals, and carcass saponafiable fat tended to be reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Perinephric abscess: the missed diagnosis.

Perinephric abscess is a life-threatening but treatable process. Most infections of the perinephric space occur as a result of extension of an ascending urinary tract infection, commonly in association with nephrolithiasis or urinary tract obstruction. A large portion of the mortality is the result of failure to diagnose this entity in a timely fashion. This failure may be because of the frequently obscure or nonspecific nature of the clinical presentation. Blood cultures as well as urine cultures may fail to identify correctly the bacterial pathogens responsible for the abscess. Perinephric abscess should be considered in the differential diagnosis of any patient presenting with a urinary tract infection that fails to respond promptly to antibiotic therapy, particularly in those known to have anatomical abnormalities of the urinary tract or diabetes mellitus. Consideration of this diagnosis should enter into the differential diagnosis of fever with abdominal pain or flank pain. Early recognition of perinephric abscess and prompt drainage, either percutaneously or surgically, in combination with appropriate antibiotic coverage, should reduce dramatically the morbidity and mortality from this infection.

Large-scale purification of antisense oligonucleotides by high-performance membrane adsorber chromatography.

Very high flux ion-exchange membranes were utilized for a novel purification of antisense oligonucleotides (20-mer). Strong anion-exchange membranes were produced by attaching polymeric ligands onto a microporous cellulosic matrix. The oligonucleotides purified were therapeutic single-stranded phosphorothioates deoxyribonucleotides. Although small-scale membrane devices (15 cm2) had similar resolution to traditional chromatographic columns; their throughputs were superior. Greater than a 1300-fold scale-up produced very similar purity and yields of the phosphorothionate product. Scale-up experiments were conducted with a 2 m2 surface area membrane module. These modules were easily capable of very high throughputs of 0.5 to 2 l/min. High purity and yields were achieved by both step and linear gradient elution.

Studies on the scale-up of microfiltration membrane devices.

This paper addresses the prediction and modeling of fouling in microfiltration (MF) membrane devices during the filtration of biological solutions. The membrane-fouling model described can be used by bioengineers to characterize a solution's filterability when using a specific microfiltration product line. This allows bioengineers to predict the scale up of filtration from laboratory through clinical production to full marketing production. The model used to correlate filtration results contains two parameters (initial flux and membrane plugging constant) that must be determined experimentally. Once these parameters are known, it is possible to predict the performance (fouling and throughput) of larger membrane devices as a function of operating pressure, processing time, and membrane area. This allows users of MF devices to perform laboratory tests of their solution at relatively small scale, and based on these tests determine the performance of larger-scale MF devices for filtration of the same solution.

Studies on the scale-up of crossflow filtration devices.

This paper describes a new method that makes it possible to predict the performance of crossflow ultrafiltration and microfiltration when scaling up from small laboratory scale to process-scale systems. Using this method, one characterizes a solution's filtration properties with a specific ultrafiltration or microfiltration membrane in a laboratory-scale crossflow device. Based on experimental results at this scale, one can accurately predict scale-up performance from laboratory through clinical production to full marketing production. Given the need for biopharmaceutical engineers to rapidly predict the size and cost of full-scale filtration processes once products receive regulatory approval, this method will find wide use in the pharmaceutical industry.

US-Hungarian partnership: strengthening home care's stand.

A partnership established between a US home care provider and a hospital in Hungary dedicated itself to reducing the length of hospital stays by strengthening home care in Vac, Hungary. With other similar ventures, the accomplishments of the partnership can be disseminated throughout other parts of Hungary and central and eastern Europe.

Proteinuria, hyperlipidemia, and the kidney.

Hyperlipidemia in the nephrotic syndrome is the result of abnormalities in both synthesis and catabolism of lipids and lipoproteins. The etiology of nephrotic hyperlipidemia has not been established, but both abnormal glomerular permeability to plasma proteins and reduced serum oncotic pressure may contribute. Although standard hypolipemic drugs are effective in nephrotic patients, therapies such as dietary protein restriction and angiotensin-converting enzyme inhibitors which reduce proteinuria and increase serum oncotic pressure ameliorate hyperlipidemia as well. Hyperlipidemia may also induce proteinuric renal disease in normal animals and worsen renal injury in a variety of animal models of kidney disease. Conversely, treatment of hyperlipidemia prevents renal injury and lessens proteinuria. Potential mechanisms by which hyperlipidemia may cause renal injury include inflammatory and immunologically mediated injury and alteration of glomerular paracrine function.

Hormonal modulation of proteinuria in the nephrotic syndrome.

Proteinuria is the primary manifestation of a variety of glomerular diseases which are characterized clinically by the nephrotic syndrome. In many cases there is little effective treatment for the primary disease process. However, reduction of proteinuria can frequently improve the hypoalbuminemia, hyperlipidemia and edema which are responsible for the morbidity of the nephrotic syndrome. Proteinuria can be reduced in nephrotic humans and experimental animal models by restriction of dietary protein intake, nonsteroidal anti-inflammatory drug, and by angiotensin-converting enzyme inhibitors. Each of these therapies modifies the activity of locally acting glomerular hormones, autocoids, suggesting that there is a component of proteinuria which is hormonally mediated. The effects of dietary protein, nonsteroidal anti-inflammatory drugs, and angiotensin-converting enzyme inhibitors on nephrotic proteinuria and their potential hormonal mechanisms of action is the subject of this review.

Resolution of acute renal failure in toxoplasmic encephalitis despite continuance of sulfadiazine.

A patient with AIDS and toxoplasmic encephalitis treated with pyrimethamine and sulfadiazine became hypovolemic and developed acute renal failure. Diagnostic sulfadiazine crystals were abundant in the urine, and ultrasound examination demonstrated sludge and stones, presumably due to sulfadiazine. Renal failure resolved rapidly with hydration and administration of alkali, despite continued administration of sulfadiazine. The relatively old literature concerning crystalluria and renal failure due to sulfonamides is reviewed briefly, since complications due to use of poorly soluble sulfonamides probably will become more widespread as toxoplasmic encephalitis becomes more prevalent.

Albuminuria causes lysozymuria in rats with Heymann nephritis.

To determine if changes in dietary protein intake alter renal excretion of small molecular weight proteins in passive Heymann nephritis, 21 rats with passive Heymann nephritis were fed 8.5% protein for 12 days after injection with antiserum. Dietary protein intake was then increased to 40% in 10 rats (LP-HP) while 11 rats remained on 8.5% protein (LP-LP). Lysozymuria (UlysV) increased from 66.5 +/- 31.0 mcg/day to 457.5 +/- 98.0 mcg/day (P less than 0.001) after five days in LP-HP, but was unchanged in LP-LP. Albuminuria (UalbV) increased only in LP-HP, from 168 +/- 23 mg/day to 447 +/- 45 mg/day (P less than 0.001). Urinary lysozyme excretion correlated with UalbV (r = 0.737, P less than 0.001), and changes in UlysV correlated with changes in UalbV (r = 0.657, P less than 0.01). To determine whether the increase in UlysV was the direct effect of the change in diet, enalapril 40 mg/kg/day was administered to prevent the increase in UalbV that occurs when these rats are fed a high protein diet. Twelve rats were fed 8.5% (LP) and 10 were fed 40% protein (HP) from the time of injection with antiserum. Six LP (LPE) and five HP (HPE) received enalapril. UlysV was 873 +/- 391 mcg/day in HP and nearly undetectable in the other three groups. UalbV was significantly greater in HP (368 +/- 60 mg/day) compared to the other three groups (114 +/- 16 in LP, 136 +/- 44 in HPE, 95 +/- 21 in LPE.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of modulation of renal kallikrein-kinin system in the nephrotic syndrome.

Albuminuria (UAlbV) can be reduced by converting-enzyme inhibitors (CEI), but the hormonal mechanism responsible for this effect has not previously been defined. Since CEI increase kinin activity as well as reduce angiotensin II (ANG II) activity, experiments were performed to determine the effect of isolated alterations in kinin and ANG II metabolism on UAlbV in rats with passive Heymann pephritis. Phosphoramidon was used to potentiate kinin activity without altering ANG II synthesis. Aprotinin was utilized in combination with the CEI, enalapril, to prevent the increase in kinin activity caused by CEI. UAlbV and the fractional renal clearance of albumin (FCAlb) decreased significantly after either phosphoramidon or enalapril, although only enalapril reduced blood pressure. Glomerular filtration rate (GFR) was not affected by either drug. Phosphoramidon did not affect plasma renin activity (PRA) or the pressor response to angiotensin I (ANG I), indicating that ANG II synthesis was not altered. Aprotinin prevented the reduction in UAlbV and FCAlb produced by CEI but not the hypotension, elevated PRA, or ANG I pressor blockade produced by CEI. Aprotinin alone had no effect on UAlbV, GFR, PRA, or blood pressure. UAlbV can be reduced by increasing kinin activity by a mechanism that is not dependent on suppression of ANG II activity or reduction in GFR or blood pressure. CEI may reduce proteinuria as a result of their action on the kallikrein-kinin system rather than on the renin-angiotensin system.

Effect of some environmental factors on cyanophage AS-1 development in Anacystis nidulans.

The development cycle of the cyanophage AS-1 was studied in the host blue-green alga, Anacystis nidulans, under conditions that impair photosynthesis and under various light/dark regimes. Under standard conditions of incubation the 16-h development cycle consisted of a 5-h eclipse period and an 8-h latent period. Burst size was decreased by dark incubation to 2% of that observed in the light. An inhibitor of photosystem II, 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), reduced the burst size to 27% of that of the uninhibited control, whereas cyanophage production was completely abolished by carbonyl-cyanide m-chlorophenyl hydrazone (CCCP), an inhibitor of photosynthetic electron transport. Dark incubation of infected cells decreased the latent period by 1-2 h and the eclipse period by 1 h, once the cultures were illuminated. This suggests that adsorption took place in the dark. Intracellular growth curves indicated that light is necessary for viral development. Infected cells must be illuminated at least 13 h to produce a complete burst at the same rate as the continuously illuminated control. Low light intensities retarded the development cycle, and at lowest light intensities no phage yield was obtained. AS-1 is highly dependent on host cell photophosphorylation for its development.

The antiproteinuric action of angiotensin-converting enzyme is dependent on kinin.

Converting enzyme inhibitors (CEI) reduce proteinuria in nephrotic humans and animals, but the mediator(s) of this effect has not been identified definitively. To determine whether enhanced kinin activity contributes to the antiproteinuric action of CEI, rats with passive Heymann nephritis were treated with the B2 kinin receptor antagonist HOE 140, 300 micrograms/kg per day, for 3 days and then the CEI enalapril (ENAL), 35 mg/kg per day, was given for another 4 days while HOE 140 was continued (HOE/ENAL). Additional groups of nephrotic rats were untreated (CON), received HOE 140 only (HOE), or received ENAL only. ENAL alone produced a > 60% decrease in albuminuria after 4 days, whereas HOE 140 alone had no effect on albuminuria. In HOE/ENAL, pretreatment with HOE 140 prevented the decrease in albuminuria observed in ENAL. GFR increased significantly over time in all groups but was not different among the groups on any day. The clearance of albumin decreased significantly in ENAL (P < 0.001) and was significantly lower than in CON, HOE, or HOE/ENAL on Day 10. The fractional clearance of albumin decreased in all groups as a result of the increase in GFR but was significantly lower in ENAL compared with the other three groups at Day 10 and was not different between CON, HOE, and HOE/ENAL. Plasma renin activity and concentration were increased significantly in both ENAL and HOE/ENAL, indicating that converting enzyme was effectively inhibited in both groups. It was concluded that enhanced kinin activity contributes to the antiproteinuric action of CEI in this model of nephrotic syndrome.

Cyanophycin granule polypeptide formation and degradation in the cyanobacterium Aphanocapsa 6308.

The effect of a number of conditions on the amount of cyanophycin granule polypeptide [multi-L-arginyl poly(L-aspartic acid)] formed in the unicellular cyanobacterium Aphanocapsa 6308 was determined. Light, CO2, sulfur, and phosphorus starvation as well as the addition of arginine to culture media increased the amount of cyanophycin granule polypeptide in cells when compared with that in cells grown under conditions optimal for growth. Nitrogen limitation and reduction of growth temperature to 30 degrees C decreased the amount of cyanophycin granule polypeptide on a dry-weight basis. Shift-up and shift-down experiments suggest cyanophycin granule polypeptide may be a reserve nitrogen polymer in Aphanocapsa 6308.